Ethylene, butadiene production



Oct. 3, 1967 J. F. HUTTO ETAL ETHYLENE,` BUTADIENE PRODUCTION 4 Sheets-Sheet l Filed Sept. 4, 1964 Oct. 3, 1967 I'iled Sept. 4, 1964 (IIS J. F. HUTTO ETAL ETHYLENE, BUTADIENE PRODUCTION 4 Sheets-Sheet 3 IIB NAPHTHA fm v ETI-IYLENE ORAOKING SEPARATION '5H |2|f |221 HEAVIES] `fl-||9 BUTADIENE CBUTAD'ENE RECOVERY Izs DlsPRORORTIONATlONr I-BUTENE ORAOKING [|29 SEPARATION ISOBUTYLENE REMOVAL |sOBuTYLENE Y L /IaI 2-BUTENE CRAOKING L /NvE/vro/Ps JF. HUTTO RE. DIXON J.w. OAvlsON c A. AYREs @.A. RENBERG OR.v

00h 3, 1957 J. F. HUTTo ETAL ETHYLENE, BUTADIENE PRODUCTION 4 Sheets-Sheet 4 Filed Sept. 4.-, 1964 United States Patent O 3,345,285 ETHYLENE, BUTADIENE PRODUCTION John F. Hutto, Rolland E. Dixon, Joseph W. Davison,

Charles A. Ayres, Graham A. Renberg, and Donald K. MacQueen, Bartlesville, Okla., assignors to Phillips Petroleum Company, a corporation of Delaware Filed Sept. 4, 1964, Ser. No. 394,581 9 Claims. (Cl. 208-67) This invention relates to hydrocarbon conversion. In one aspect the invention relates to a method and apparatus for combined naphtha cracking, olefin disproportionation and olefin dehydrogenation. In another aspect the invention relates -to the combined processing of the effluent of a cracking furnace and the effluent of an olefin dehydrogenation. In another aspect the invention relates to removing a heavy fraction prior to subsequent removal of lighter fractions lfrom a hydrocarbon stream. In another aspect the invention relates to use of a single deethanizing step and deethanizer to treat the feed to and the effluent from a propylene disproportionation. In another aspect the invention relates to removal of C4 paraffins from a side stream to prevent build-up in a butene dehydrogenation feed stream. In another aspect the invention relates to combining butylenes from a butadiene recovery section and from a disproportionation step to produce a feed to a dehydrogenation unit. In another aspect the invention relates to the separation of the effluent from a disproportionation reactor and recycle of appropriate products.

In this application disproportionation is used to mean the conversion of a hydrocarbon into similar hydrocarbons of higher and lower numbers of carbon atoms per molecule. Such an operation is useful in many instances. For example, a more plentiful hydrocarbon can be converted to a less plentiful and, therefore, more valuable hydrocarbon. Where the reactant comprises 1- or 2-olefins, a mixture of new products is obtained comprising primarily olefins having both a larger and a smaller number of carbon atoms than the feed olefin but also including some other disproportionated products, for example, saturated hydrocarbons and other converted and unconverted material.

Disproportionation can be accomplished using a catalyst comprising molybdenum oxide and aluminum oxide and preferably also an oxide of cobalt, or other disproportionation catalyst, to produce a disproportionated product comprising a very small quantity of saturated hydrocarbons and a relatively small amount of branched chain olefins.

Butadiene conventionally is produced by the dehydrogenation of butane in one or two steps. The production by such a process entails a very difficult separation problem since a stream containing butane, l-butene, 2-butene and butadiene is produced.

Propylene often is available in excess quantities as a result of the cracking operations. Although some of the propylene can be used, for example, for alkylation, some for polymerization to polypropylene resins or for propylene tetramer for use in the manufacture of detergents, often there still remains a quantity of propylene for which it is difficult to find a use. On the other hand, other olefins, ethylene on the one hand and butene on the other hand, for example, are in demand, the ethylene for the ICC production of ethylene polymers for example and butene for the production of butadiene as indicated above. By disproportionating propylene, both ethylene and butene can be produced.

When ethylene is unavailable in a desired location, it is difficult to ship because of the high pressure and/o1' refrigeration required to ship in reasonably large quantities. By the practice of my invention, ethylene can be provided at such locations by the conversion of propylene by disproportionation. The propylene and the C4s fed to the dehydrogenation unit both result from the cracking of naphtha in one aspect of our invention.

An object of our invention is to produce ethylene and butadiene -from naphtha. Another object of our invention is to reduce the separation facilities required in a combined naphtha cracking and butene dehydrogenation operation.

Another object of our invention is to convert propylene to more valuable higher and lower olefins.

Another object of our invention is to facilitate plural fractionation steps by early removal of a heavier fraction.

Another object of our invention is to make efficient use of separation facilities both on the feed and the effluent of a disproportionation reaction.

Another object of our invention is to prevent the buildup of C4 paraffins in a butene dehydrogenation feed stream.

Another object of our invention is to provide a feed stock for dehydrogenation.

Another object of our invention is to provide efficient separation of disproportionation products.

Other aspects, objects and advantages of our invention are apparent in the written description of the drawing and the claims.

According to our invention, a hydrocarbon stream is cracked, the effluent separated to produce a feed stream suitable for feed to a dehydrogenation step and the efliuent from the dehydrogenation step is fed to the same separation apparatus. Further according to our invention, there is also produced in the separation apparatus a stream suitable for use as a feed to an olefin disproportionation unit and efiiuent from the disproportionation unit also is returned to the separation apparatus at the proper point. Further according to our invention, fractionation of a multi-component hydrocarbon stream is facilitated by removing a heavy fraction prior to subsequent removal of lighter fractions.

Further according to our invention, eicient use is made of separation facilities by separating components of the eiiiuent of a disproportionation reaction in the same facilities utilized for separating components from the feed to the disproportionation reaction.

Further according to our invention prevention of buildup of butane in a butadiene manufacturing system is prevented by removal of butane from a side stream of the main feed stream.

Further` according to our invention a first dehydrogenation feed stream is produced by naphtha cracking followed by separation of products not desired in the hydrogenation, a second dehydrogenation feed stream is produced by propylene disproportionation followed by separation of products not desired in the dehydrogenation and combining the first and second feed streams prior to feeding into the dehydrogenation zone.

Further according to our invention, build-up of propane in a disproportionation system wherein propylene and propane are recycled to the `disproportionation reaction zone, by passing the disproportionated stream into a first separation Zone, removing the first separation stream which comprises substantially all of the ethylene in the disproportionated stre-am, -a second stream comprising substantially all of the butene with a minor amount of propylene and an amount of propane substantially equal to the net amount of propane entered in the process, and a third stream comprising the major proportion of the propylene and propane, transferring the second stream into a second separation zone, removing a fourth stream comprising substantially all of the butene and a fifth stream comprising substantially all of the propane in the amount in the second separated stream and recycling the third stream tot the disproportionation zone.

Further according tor our invention, the build-up of propane in a propylene disproportionation system is avoided by passing the disproportionated stream into a separation zone, removing a stream comprising ethylene, and a stream comprising butene, and recycling a stream comprising propylene and propane, and withdrawing from the system a relatively small amount of the recycled stream.

Further according to our invention, dehydrogenation, in a broad sense, relates to any suitable reaction producing dehydrogenated products corresponding with `the feed stream. For example, a reaction yspecifically directed toward dehydrogenation of butene to produce butadiene is included as well as a butene cracking step which also lproduces butadiene as well as other products.

Further according to our invention, butene produced from naphtha cracking is further cracked to produce butadiene, 2-butene produced from the same naphtha cracking also is cracked to produce additional butadiene and Z-butene resulting from the disproportionation of propylene produced in the naphtha cracking is combined in the Z-butene cracking zone.

Oiur invention relates to process aspects and to apparatus aspects.

The disproportionation of olefins can be accomplished, as disclosed and claimed in Ser. No. 127,812, Banks, filed July 31, 1961, now abandoned; Ser. No. 307,371, Heckelsberg filed Sept. 9, 1963; Ser. No. 94,996, Banks, filed March 13, 1961; and a copending application entitled Olen Disproportionation, Banks, filed Sept. 27, 1963, or by other process, using a catalyst comprising molybdenum oxide and aluminum oxide and preferably also an oxide of cobalt, tungsten oxide o-n alumina, molybdenum oxide or tungsten oxide on silica, or on silica-alumina, tungsten carbonyl or molybdenum carbonyl on silica, alumina or silica-alumina, or other variations of these catalysts, tungsten sulfide or molybdenum sulfide on alumina or other disproportionation catalysts to produce a disproportionated product comprising a very small quantity of saturated hydrocarbons and a relatively small amount of branched chain olefins. Where the reactant comprises 1- or 2-olefins, a mixture of new products is obtained comprising primarily olefins, some having a larger and some a smaller number of carbon atoms than the feed, and also including some other disproportionated products. Conditions can be controlled to obtain a veryhigh efficiency of conversion to desired disproportionation products. For example, propylene can consistently be converted to ethylene and butenes with an elicency above 95 percent.

Any catalyst suitable yfor disproportionating olefins can be used in the practice of our invention. One catalyst used in our invention comprises.y an oxide of aluminum promoted by an oxide of molybdenum and, preferably, additionally promoted by an oxide of cobalt. Suitable supports include 100 percent alumina, silicaalumina wherein the amount of silica is up to about 25 Ipercent of the total support, magnesia-alumina wherein the amount of magensia is up to about 20 percent of the total support, and titania-alumina wherein 5 the amount of titania is up to about S5 percent of the total support.

The amount of molybdenum oxide or tungsten oxide is in the range of 0.5 to 30 percent by weight of the total catalyst composition, preferably 1 to 15 percent. Cobalt oxide can be present in the molybdenum promoted catalyst in the range of to 20 percent by weight of the total catalyst, preferably l to percent. Excellent results with high conversion have been obtained with molybdenum oxide in the range of 4 to 13 percent by weight of the total catalyst.

The composite catalyst can -be prepared by any conventional method such as dry mixing, coprecipitation or impregnation. For example, a -100 mesh alumina (having a 178 m.2/g. surface area and la 107 A. pore diameter) is impregnated with an aqueous solution of a molybdenum compound, such as ammonium molybdate, which is convertible to the oxide upon calcination. A commercially available catalyst comprising 12.8:3.8:83.4 MoO3-CoO-Al203 having a 208 rn.2/g. surface area and and a 96 A. pore diameter is also satisfactory, the ratios being by weight. A suitable heat activation treatment can be performed where necessary or desirable to give an olefin disproportionation active catalyst.

The process of our invention can be carried out either batchwise or continuously, using a fixed catalyst bed, or a stripper equipped reactor or other mobile catalyst contacting process as well as `any other well known contacting technique. Preferred reaction conditions, eg., temperature, pressure, flow rates, etc., vary somewhat depending upon the specific catalyst composition, the particular feed olefin, desired products, etc. The temperature, pressure, and contact times are selected for the particular catalyst to give the desired disproportionation conversion with ,the feedstock used.

The disproportionation reaction can be carried out either in the presence or absence of a diluent. Diluents selected from the group consisting of paraflinic and cycloparainic hydrocarbons can be employed. Suitable diluents are, for example, propane, cyclohexane, methylcyclohexane, normal pentane, nor-mal hexane, isooctane, dodecane, and the like, or mixtures thereof, including primarily those parains and cycloparans having up to l2 carbon atoms per molecule.

In the dehydrogenation step, catalyst, conditions, etc., for producing diolefins from olefin feedstocks are well known and need not be discussed in detail at this point. For example, a suitable dehydrogenation process is disclosed in U.S. Patent No. 2,866,790.

In the drawings, FIGURE 1 illustrates a unitized system for naphtha cracking, propylene disproportionation, and butene dehydrogenation, for the production of ethylene and butadiene, along with by-products.

FIGURE 2 illustrates another embodiment of the disproportionation and separation system.

FIGURE 3 illustrates a combination of naphtha cracking, propylene disproportionation and butene cracking, producing ethylene and butadiene and by-products.

FIGURE 4 illustrates a unitized system for naphtha cracking, propylene disproportionation, and butene dehydrogenation, utilizing a simplified separation system.

Referring to FIGURE 1, a naphtha stream is passed into naphtha cracker 11 through conduit 12 and the effluent passed to heat recovery and quench 13 through conduit 14. In the heat recovery and quench section 13, the effluent from the naphtha cracking furnace is quenched in waste heat boilers, and a two-stage quench tower provides for subequent cooling by passing the vapors upwardly through the tower, the lower section of `which is an oil quench and the upper section a multiple water quench. For further conservation of heat, steam is generated in waste heat boilers in the cracking furnace stack gas system. A fuel oil condenses in the quench tower and is removed as a side stream Afrom the circulating quench oil.

The elfluent from the quench tower is compressed and fed to debutanizer as one vapor stream and two condensate streams. This is accomplished by passing the effluent from heat recovery and quench section 13 through compressor 16 into ash chamber V17, the condensate beingpassed to debutanizer 15 through conduit 19 while the overhead is compressed in compressor 21 and passed to flash chamber22 from which the condensate is passed to debutanizer`15 through conduit 23 and the vapor is transferred to debutanizer 15 through conduit 24. A debutanized gasoline stream is removed as a bottoms product from debutanizer 15 through conduit 26.

The overhead is further compressed in compressor 27 and passed through an amine treating unit for the removal of CO2 and HZS. The effluent from amine treater 28 is passed to caustic wash and dry unit 29 Where the eiiluent from the amine unit is caustic washed to remove the last traces of acid gases, then water washed to prevent caustic carry over. The eluent from caustic wash and dry unit 29 is fed to depropanizer 30. The butane and heavier bottoms product from depropanizer 30 is passed through conduit 31 to the butadiene recovery and purication unit, the iirst stage being a furfural absorber 32. Butadiene is absorbed in absorber 32 and the -rich furfural passed into furfural stripper 33, furural being returned to furfural absorber 32 through conduit 34, and the butadiene rich stream passed through conduit 35 into butadiene column 36. A high purity butadiene stream is taken overhead through conduit 37, and the bottoms product, comprising butenes, is passed through conduit 38 into conduit 39 which feeds butene deoiler 40.

The overhead from the furfural absorber is separated into two streams, one stream being passed through conduit 41 into a cold acid isobutylene removal unit 42 while the outher stream is passed through conduit 41 and conduit 43 into butene extraction column 44 which controls the build-up of butanes in the system by removal of butanes from this side stream. The debutanized stream from extraction column 44 is passed through conduit 45 and recombined with the stream being fed to isobutylene removal unit 42. The deoiled overhead from butene deoiler' 40 is passed into butene dehydrogenation reactor 46 and the el'luent passed through conduit 47 to the separation system for the eiiuent from naphtha cracker 12.

Preferably, the euent from the dehydrogenation reactor is quenched in a waste heat boiler and cooled in a stack oil 'and water quench tower similar to the naphtha cracking furnace effluent heat recovery and quench system.

The propane and lighter fraction from depropanizer 30 is compressed in compressor 51 and passed into the primary lacetylene removal reactor 52. 'Ihis unit is operated under high selectivity, lou/,conversion conditions to remove the bulk'of C2 and C3 acetylenes, piperidene, and butadiene, without significant losses of ethylene or propylene. Preferably this stream again is dried to remove water formed from oxygen compounds in the acetylene removal reactor feed and then fed to cooling train 53. Cooling train 53 is a series of refrigerated and recycled cooled heat exchangers and a centrifugal expander, with corresponding required auxiliary surge tanks, pumps, etc. A hydrogen rich vapor and a methane rich vapor are removed as by-products, and the remainder of the stream is liqueed and sent to demethanizer 54. Preferably the demethanzer overhead is recycled through the cooling train for sensible heat recovery and then is produced fas a -fuel gas-byproduct. The demethanizer bottoms, primarily ethane, ethylene, propane and propylene, are fed through conduit 56 into deethanizer 57. The deethanizer overhead is fed through conduit 58 into secondary acetylene removal reactor 59, operated at high conversion and low selectivity, to bring the acetylene content to a low value. The etlluent from the secondary acetylene removal reactor is fed to ethylene fractionator 61 'and separated into an overhead ethylene stream and a bottoms product ethane stream. The ethane stream is removed through conduit 62 while the ethylene stream is passed through conduit 63 to methane stripper 64, with high purity ethylene being removed through conduit 66. Where suicient demand for ethylene exists, the produced ethane can be cracked to produce additional quantities of ethylene. The overhead from methane stripper 64 contains sufficient ethylene to justify reseparation, and this stream is recycled to the suction of compressor 51 through conduit 67 as shown.

The bottoms product from deethanizer 57 is passed through conduit 71 to an acetylene removal unit 72. This unit is operated at high conversion, low selectivity, to reduce the methylacetylene Iand propadiene concentration suiliciently to prevent damage to the disproportionation catalyst. The eruent from acetaylene removal unit 72 is fed to disproportionation reactor 73. The effluent from reactor 73 is passed through conduit 74 to propylene splitter 76. The overhead, comprising ethylene and lighter, is recycled to deethanizer 57 through conduit 77. A side draw, primarily propylene and propane, is recycled through conduit 78 to the inlet of reactor 73. The bottoms product, propane and heavier, is fed to depropanizer 81 through conduit 82 and the bottoms product from depropanizer 81 is fed through conduit 83 into the inlet for butene deoiler 40.

In the embodiment of FIGURE 2, the effluent from the disproportionation reactor 101 is passed through conduit 102 into a fractional distillation column 103. The overhead from column 103, comprising substantially al1 of the ethylene which is fed to column 103 through conduit 102, and smaller quantities of propylene and propane, is returned through conduit 104 to deethanizer 106. The overhead from deethanizer 106 is passed to ethylene fractionator 107 through conduit 108. The side draw of column 103, which is removed through conduit 109, comprises a very large portion of the propane and propylene fed through conduit 102, along with a minor amount of ethylene. The major portion of this stream is recycled to disproportionation reactor 101 through conduit 111, combined with the bottoms y'product from deethanizer 106 which is passed through conduit 112 while a minor amount of the side draw is bled through conduit 113 to prevent buildup of propane. The bottoms product from column 103, comprising substantially all of the butenes which are fed through conduit 102, along with t-race amounts of other materials, is passed through conduit 114 to a butene dehydrogenation unit. By the use of the system illustrated in FIGURE 2, the necessary separations for recovery of ethylene, recycle of propylene and propane, the feeding of butenes to butene dehydrogenation, and the prevention of propane build-up all are accomplished with a single column. The butene dehydrogenation referred to can be either a speciic dehydrogenation unit as described above in connection with FIGURE 1 or can be a butene cracking unit as described below with respect to FIG- URE 3.

Where maximum production of butadiene is important, a specific butadiene dehydrogenation step is preferred. However, very substantial quantities of butadiene, comprising a large part of the potentially available butadiene, can lbe produced with a very much smaller investment in operating costs, by using butene cracking steps as illustrated in FIGURE 3. In the system of this ligure, the naphtha cracking effluent from reactor 116 is passed through conduit 117 to separation unit 118. From separation unit 118 a heavier stream, such as a depropanized gasoline stream and fuel oil, is rremoved as illustrated schematically by conduit 119. A C4 hydrocarbon stream is passed through conduit 121 into butadiene recovery unit 7 122, similar to the butadiene recovery unit illustrated and described with respect to FIGURE 1 above. However, preferably l-butene is removed separately from Z-butene, the 1-butene being passed to isobutylene removal unit 124 `and to 1-butene cracking unit 123, and the 2-butene being passed through conduit 126 to 2-butene cracking unit 127.

The C3 hydrocarbon stream is passed to disproportionation unit 128 and the euent, after separation in unit 129, comprising primarily 2-butene, is passed through conduit 131 into Z-butene cracking unit 127. The effluent from cracking unit 123 and cracking unit 127 are passed into separation unit 118.

It is also possible to crack 1- and Z-butene in the same reactor.

Example l In an example of the operation lof our invention according to FIGURE 1, the stream fed to cracking reactor 11 comprises a wide range naphtha made from a Kuwait crude, the naphtha having a boiling range of 105 to 352 F., density of 64.3 API and comprising 72 volume percent parain (44 percent N-parain), 18 percent by volume naphtha and percent by volume aromatics, with substantially no olens. The operating conditions of the various units of the system are given in Table I, and a material balance is presented in Table II, the numbers of the streams corresponding with numbers in FIGURE 1.

Example II In an example according to FIGURE 2, all of the conditions are the same as the conditions of FIGURE 1 for all the units not shown in FIGURE 2, including naphtha cracking, butene dehydrogenation, etc. In the portion illustrated in FIGURE 2, the conditions in the various units are given in Table III and the material balance ofthe various streams in Table IV.

Example III In an example according to FIGURE 3, the conditions in the various units are given in Table V and the material balance in Table VI. The feed stream is the naphtha of Example I. Conditions not given in Table V and material balance values not listed in Table VI are the same as corresponding values in the system of Example I.

TABLE 1.-OPERATING CONDITIONS 22 2nd Flash:

1I10 p.s.i.a., 60 F. Debutanizer:

Reflux drum: 100 p.s.i.a., 62 F. Reboiler vapor: 110 p.s.i.a., 313 F. 27 3rd Compressor stage:

Inlet: 100 p.s.i.a., 62 F. Outlet: 255 p.s.i.a., 185 F. 2150 Horsepower, 3479 c.f.rn. Amine treater:

Absorber tower: 250` p.s.i.a.; 160 F. in, 135 F.

out 95% CO2 removal.

Caustic wash and dry:

Caustic tower: 245 p.s.i.a., 135 F. Water wash tower: 250 p.s.i.a., 135 F. Dryer inlet: 230 p.s.i.a., 60 F. Dryer outlet: 210 p.s.i.a., 60 F. Depropanizer:

Reux drum: 200 p.s.i.a., 0 F. Reboiler vapor: 210 p.s.i.a., 202 F. Furfural absorber:

Reflux drum: 100 p.s.i.a., 138 F. Reboiler vapor: 120 p.s.i.a., 303 F. Furfural stripper:

Reflux drum: 65 p.s.i.a., 1\10 F. Reboiler Vapor: p.s.i.a., 329 F. Butadiene column:

Reux drum: 75 p.s.i.a., 105 F. Reboiler Vapor: 90 p.s.i.a., 161 F. Butene deoiler:

Overhead vapor: 85 p.s.i.a., 136 F. Reboiler vapor: p.s.i.a., 186 F. Isobutylene removal:

Standard cold sulfuric acid extraction. Butane extraction column:

Tower top: 1110 p.s.i.a., F. Tower bottom: p.s.i.a., 150 F. Extractant: Furfural. Butene dehydrogenation reactor:

Phillips R-1490 catalyst. Reactor pressure: 17.5 p.s.i.a. Inlet temperature: 1302 F. Outlet temperature: 1223 F. Steam/HC ratio: 12. 4th Compressor stage:

Inlet: 198 p.s.i.a., 60 F. Outlet: 525 p.s.i.a., 230 F. 1750 Horsepower, 1292 c.f.m. Primary acetylene removal unit:

Girdler G-73 catalyst. Reactor conditions: 520 p.s.i.a., 350 F. Cooling train:

13 refrigerated and interchanger units in series.

97 Horsepower centrifugal expander.

Inlet: 485 p.s.i.a., 55 F.

Outlets: 480 p.s.i.a., 10 F.

470 p.s.i.a., 84 F. 466 p.s.i.a., 150 F.

Hydrogen separator: 455 p.s.i.a., 200 F. Demethanizer:

Reux drum: 425 p.s.i.a., 142 F.

Reboiler vapor: 435 p.s.i.a., 52 F. Deethanizer:

Reux drum: 400 p.s.i.a., 14 F.

Reboiler vapor: 4410 p.s.i.a., 147 F. Secondary acetylene removal unit:

Girdler G-58 catalyst i12/C2H2 ratio: 2.0.

Reactor conditions: 395 p.s.i.a., 350 F. Ethylene fractionator:

Reux drum: 290 p.s.i.a., 25 F.

Reboiler vapors: 300 p.s.i.a., 3 F. Methane stripper:

Reux drum: 300 p.s.i.a., 29 F.

Reboiler vapors: 310 p.s.i.a., 17 F. C3 acetylene removal unit:

Girdler G-55 catalyst.

H2/C3H4 ratio: 2.0.

Reactor conditions: 485 p.s.i.a., 350 F. Propylene disproportionation unit:

Reactor conditions: 460 p.s.i.a., 850 F. Propylene splitter:

Reflux drum: 420 p.s.i.a., 114 F.

Reboiler vapor: 430 p.s.i.a., 239 F. Propane stripper:

Reflux drum: 265 p.s.i.a., 123 F.

Reboiler vapor: 275 p.s.i.a., 246 F.

TABLE II.MATERIAL BALANCE, POUNDS PER HOUR Stream Number Component Hydrogen 6,347 2 1 1,187 o o Carbon Monoxide O 0 0 179 0 0 Carbon Dioxide 106 31 22 2, 781 0 0 Meth 12, 036 30 24 12, 935 0 0 248 33 18 265 6 98 98 98 98 18, 898 183 138 18, 778 Ethane 6, 124 91 71 6, 181 0 0 Propylene 15, 414 739 525 l5, 317 0 158 Propane 1, 372 120 86 2, 296 0 25 Isobutane- 243 94 59 624 0 771 2, 006 321 187 1, 851 0 2, 355 1, 345 1, 433 885 7, 886 0 10, 193 2, 745 1, 431 1, 228 9, 723 0 12, 377 602 287 7 1, 316 0 1, 779 1, 777 2, 396 1, 306 9, 694 6 13, 389 958 1, 727 954 6, 846 293 9, 234 34, 841 31, 242 3, 024 561 34, 480 348 Heating Oil.- 6,229 0 0 0 0 0 Total Hydrocarbons-.- 105, 578 40, 160 8, 705 98, 420 34, 785 50, 727 25, 058 11, 928 13, 130 23, 798 25, 669 8, 472

Furfnr 1i 641,327 Water 40, 897

Stream Number Component Hydrogen Carbon Monoxide Carbon Dioxide Methane 2 Acetylenes Ethy1ene 5,535 1,024 Ethane 14 3 Proyplene Propane Isobut ane Isobuteno... Butene-l--- Butadiene n-Butane transButene-2 17 6, 470 6, 423 cis-Butene2 9 3,655 3,655 C5-400 Gasoline 233 Heating Oi1 Total Hydrocarbons 7, 512 48, 011 60, 550 30, 765 6, 602 24, 169 23, 821 348 29, 782 84, 775 16, 092 55, 020 13, 661 10, 668

TABLE III TABLE V Operating conditions 45 Operating conditions 101 Propylene disproportionation unit: 123 Butene-l cracking furnace:

Reactor conditions: 460 p.s.i.a., 850 F. Steam/HC ratio: 1.0. 103 Product SPhtter Outlet pressure: 25 p.s.i.a.

n O Reu?i dum- 420 P-SJ-a? 118 50 Outlet temperature: 1350-1450 F. Reboiier vapor. 430 p.s.1.a., 303 F. COnVerSion per pass: 62%. 106 Deethamzer: 127 Butene-Z crackin furnace -Reux drum: 400 p.s.i.a., 14 F. St /HC t? 10 Reboiier vapor: 41.10 p.s.i.a., 147 F.V 6am ra lo' 107 Ethylene fractionator: Oulet Pressure: 25 Ps-l-a- Reux drum; 290 p,s,i a 25 F 55 Outlet temperature: 1300-1400 Fv Reboiler vapor: 30() p.s.i.a., 3 F. Conversion per pass: 50%.

TABLE IV.MATERI A,L BALANCE Component Y 102 104 108 109 111 112 113 114 Hydrogen Carbon Monoxide Carbon Dioxide Methane 2 26 Acetylenm 4 10 Ethylene 5, 808 4, 838 22, 630 971 905 306 66 Ethano 19 13 5, 981 6 5 14 Propylene- 27, 258 4, 667 108 22, 584 21, 049 20, 191 1, 535 8 Propane- 38, 569 5, 284 11 33, 254 30, 994 7, 570 2, 260 31 Isobutane 5 5 5 Is0butene 3 3 Bllene-l 293 15 14 13 1 277 Bnfndinnn 1 n-Bnfane trans-Butene-2 5, 774 76 71 5 5, 699 ciSButene-2 3, 229 3, 229 216 216 Heating Oil Total Hydrocarbons--- 81, 177 14, 804 28, 760 56, 906 53, 038 28, 113 3, 867 9, 468

TABLE VI.-POUNDS PER HOUR Component 119 121 Heating Oil Total Hydrocarbons.

In the embodiment of FIGURE 4, the operation is somewhat similar to the operation of the system illustrated in FIGURE l, but a much simpler separation system is utilized. A naphtha stream is passed into naphtha cracker 131 through conduit 132 and the efuent passed to heat recovery and quench 133 through conduit 134. The heat recovery and quench section 133 can be 4similar to the corresponding section 13 of FIGURE 1. The eiuent from the quench tower is compressed in compressor 136 and compressor 137 and passed into ash chamber 138, the condensate from flash chamber 138 being passed to ash chamber 139. The overhead from ash chamber 138 is passed through caustic Wash and dr-y unit 141 and compressor 142 into ash chamber 143. The overhead from flash chamber 143 is passed through a heat exchange train 144 into a flash chamber 146. The condensate from chamber 146 is passed into demethanizer 147. The bottoms product from demethanizer 147 is passed into acetylene removal unit 148 and then to ethylene fractionator 149 from which an ethylene product stream is removed overhead and ethane removed from the bottom. The condensate from flash chamber 143 is passed through a C3 acetylene removal unit 151 into product splitter 152. The overhead from flash chamber 139 also passes through acetylene removal unit 151 into product splitter 152. The overhead from product splitter 152 is passed into the stream comprising the bottoms product from demethanizer 147 and passed through acetylene removal unit 148 into ethylene fractionator 149. A side draw is taken from product splitter 152 and passed to propylene disproportionation unit 153 with the product from unit 153 being returned to product splitter 152.

The bottoms product from product splitter 152 is passed into furfural absorber 155. The rich furfnral, comprising butadiene, is passed into furfural stripper 1577 and the butadiene containing stream stripped from the furfural is passed into butadiene column 158. Butadiene is removed overhead from column 158 with the bottoms product being recycled to furfural absorber 156. The rafnate from absorber 6 is passed into isobutylene removal unit 158, with isobutylene being removed therefrom and the remaining stream passed to butene deoiler 159. A slip stream, from conduit 161 which transports the ranate from absorber 156 to isobutylene removal unit 158, is taken through butane extractor 162. Butanes are removed as a rafnate from extractor 162 while the butenes are recovered and returned to conduit 1611. The overhead from butene deoiler 159 is passed into butene dehydrogenation unit 166 and a product stream is returned to compressor 136.

It Will be recognized that many elements of a complete commercial plant have been omitted from the description of the disclosed embodiment of our invention in the interests of clarity and brevity. In many instances, specific variations can be utilized, For example, any suitable disproportionation catalyst can be used in the disproportionation reactor, and any suitable butene dehydrogenation product can be used in the butane dehydrogenation reactor. Similarly, separation steps such as fractionation, solvent extraction, etc., can be utilized where appropriate and substituted by one skilled in the art. Our invention lies in combination, and therefore is not limited to a specic type of cracking, disproportionation or dehydrogenation reactor or puriication or separation steps. Many details of equipment needed in a commercial plant have been omitted, including, for example, such things as pumps, valves, control equipment, etc.

Reasonable variation and modication are possible within the scope of our invention which sets forth method and apparatus for producing propylene and butadiene from a hydrocarbon stream, along with by-products.

We claim: 1. A process 'for the production of ethylene and butadiene from hydrocarbons, which comprises the steps of:

cracking a hydrocarbon boiling Within the naphtha boiling range;

separating the cracked effluent in a rst separation zone to produce a gasoline stream, a C2 stream, a C3 stream and a C4 stream;

separating butadiene and isobutene from said C., stream and feeding said C4 stream into a butene conversion zone;

converting butene to butadiene in said butene conversion zone and combining the eiuent therefrom with said cracked effluent prior to separation thereof; passing said C3 stream to a disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene;

separating the eiuent of said disproportionation zone into an ethylene stream, a propylene stream and a butene stream;

converting butene of said butene stream to butadiene in said butene conversion zone;

recycling said propylene stream to said disproportionation zone;

combining said ethylene stream with said C2 stream;

and

separating said C2 stream into an ethylene stream and a product ethylene stream.

2. A process for olefin disproportionation, comprising the steps of:

passing a feed comprising propylene and propane into a disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene;

removing from said disproportionation zone a disproportionated stream comprising ethylene, propylene, propane and butene;

passing said disproportionated stream into a rst separation zone; in said irst separation zone removing a Iiirst separated stream comprising substantially all of said ethylene in said disproportionated stream and small amounts of propylene and propane, a second separated stream comprising substantially all of said butene in said ydisproportionated stream, a minor amount of propylene and an amount of propane substantially equal to the net amount of propane entering said process, and a third separated stream comprising the major portion of said propylene and the major portion of said propane in said disproportionated stream;

transferring said second separated stream int-o a second separation zone;

in said second separation zone removing a fourth separated stream comprising substantially all of said butene in said second separated stream and a Iiifth separated stream comprising substantially all of said propane in said second separated stream; and

recycling said third separated stream to said disproportionated zone.

3. A process for olen disproportionation, comprising the steps of passing a feed comprising propylene an-d propane into a disproportionation zone; in said disproportionation zone converting propylene to ethylene and butene; removing from said disproportionation zone a disproportionated stream comprising ethylene, propylene,

propane and butene; passing said disproportionated stream into a separation zone; in said separation zone, removing a first separated stream comprising substantially all of said butene and substantially no ethylene, propylene and propane, a second separated stream comprising the major portion of said ethylene and appreciable amounts of said propylene and propane, and a third separated stream comprising the major portion of said propylene and -the major portion of said propane; ydividing said third separated stream into a major portion and a minor portion, and recycling said major portion to said disproportionation zone. 4. A process for the production of ethylene and butadiene from hydrocarbon, which comprises the steps of:

cracking a hydrocarbon boiling within the naphtha boiling range; f

passing the eiuent of said hydrocarbon cracking into a debutanizing zone and producing a gasoline stream and a C4 hydrocarbon and lighter stream;

depropanizing said C4 and lighter stream to produce a 'C4 stream and a C3 and lighter stream;

separating butadiene, butane, and isobutene from said C4 stream and feeding said C4 stream to a dehydrogenation zone;

combining the efiiuent from said -dehydrogenation zone With said etliuent of said hydrocarbon cracking, prior to separation thereof;

removing acetylene from said C3 and lighter stream;

passing Nthe remainder of said C3 and lighterstream into a deethanizing zone;

in said de'ethanizing zone separating said remainder of said C3 and lighter stream into a C2 stream and a C3 stream;

passing said C3 stream to a disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene;

separating the eiiiuent of said disproportionation zone into an ethylene stream, a propylene stream, a propane stream and a butene stream;

feeding said butene stream to said dehydrogenation zone;

recycling said propylene stream to said disproportionation zone;

recycling said ethylene stream to said deethanizing zone;

separating said C2 stream into an ethane stream and a product ethylene stream.

5. A process for producing ethylene and butadiene,

comprising the steps of:

comprising the steps of:

cracking a hydrocarbon boiling Within the naphtha boiling range;

passing the effluent of said hydrocarbon cracking zone into a separation zone;

removing a C4 hydrocarbon stream from said separation zone and passing said C4 hydrocarbon stream into a butadiene recovery zone;

recovering a butadiene stream from said butadiene recovery zone;

removing a l-butene stream from said butadiene recovery zone and passing said l-butene stream into a 1-butene cracking zone;

removing a 2-butene stream from said butadiene recovery zone and passing said 2-butene stream into a 2butene cracking zone;

removing a C3 hydrocarbon stream from said separation zone and passing said C3 hydrocarbon stream into a disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene; 1

passing the effluent of said disproportionation zone into a second separation zone; and

removing the butene stream from said second separation zone and passing said butene stream into said Z-butene cracking zone.

7. A process for producing ethylene and butadiene,

comprising the steps of:

cracking a hydrocarbon boiling Within the naphtha boiling range;

passing the eiuentyof said hydrocarbon cracking into a separation zone;

removing a C4 hydrocarbon stream from said separation zone and passing said C4 hydrocarbon stream into a butadiene recovery zone;

removing a butadiene stream from said buta-diene recovery zone;

removing a butene stream from said butadiene recovery zone and passing said butene stream into a butene cracking zone;

passing the eiuent of said butene cracking zone into said separation zone;

removing a C3 hydrocarbon stream from said separation zone and passing said C3 hydrocarbon stream into a propylene disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene;

returning a stream comprising C2 hydrocarbons from the effluent of said disproportionation zone to said separation zone;

returning a C4 hydrocarbon stream recovered from the eluent of said disproportionation zone to said butene cracking zone; and

recovering ethylene from said separation zone.

8. A process for producing ethylene and butadiene,

comprising the steps of:

cracking a naphtha stream;

passing effluent of said naphtha cracking into a iirst ash zone;

passing condensate from said first flash zone into a second ash zone;

passing vapor from said -irst iiash zone through a caustic Wash and -dry treatment into a third flash zone;

passing vapor from said third flash zone into a fourth ilash zone;

passing condensate from said fourth flash zone into a first fractionation column;

passing bottoms product from said irstrfractional distillation column into a second fractional distillation column;

recovering ethylene overhead from said second fractional distillation column;

passing condensate from said third iiash zone and vapor from said second flash zone into a third fractional distillation column;

returning overhead product from said third fractional distillation column to said second fractional distillation column;

removing a side `stream from said third fractional distillation column and passing said side stream to a propylene disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene;

returning product from said propylene disproportionation Zone to said third fractional distillation column;

flashing bottoms product from said third fractional distillation column into a furfural absorber;

recovering butadiene from the furfural absorber;

passing rafnate from said furfural absorber into an isobutylene removal unit;

removing butanes from a side stream of said rafnate and returning the remainder of the side stream to said isobutylene removal unit;

removing isobutylene from said isobutylene removal unit;

passing the isobutylene-free stream from said isobutylene removal unit into a fourth fractional distillation column;

passing an overhead stream from said fourth fractional distillation column, comprising butenes, into a butene dehydrogenation Zone; and

returning the efuent from said butene dehydrogenation unit to said rst flash zone.

9. A process for producing ethylene and butadiene, comprising the steps of:

into a fourth recovering ethylene overhead from said second fractional distillation column;

passing condensate from said third flash zone and vapor from said second flash zone into a third fractional distillation column;

returning overhead product from said third fractional distillation column to said second fractional distillation column;

removing a side stream from said third fractional distillation column and passing said side stream to a propylene disproportionation zone;

in said disproportionation zone converting propylene to ethylene and butene;

returning product from said propylene -disproportionation Zone to said third fractional distillation column;

flashing bottoms product from said third fractional distillation column into a furfural absorber;

recovering butadiene from the furfural absorber;

passing raffinate from said furfural absorber into an isobutylene removal unit;

removing butanes from a side stream of said raffinate and returning the remainder of the side stream to said isobutylene removal unit;

removing isobutylene from said isobutylene removal unit;

passing the isobutylene-free stream from said isobutylene removal unit into a fourth fractional distillation column;

passing an overhead stream from said fourth fractional distillation column, comprising butenes, into a butene dehydrogenation Zone; and

returning the efuen-t from said butene dehydrogenation unit to said first flash zone.

References Cited UNITED STATES PATENTS 2,416,023 2/1947 Schulze et al 208-130 2,777,801 1/1957 Bittner et al. 208-79 3,113,164 11/1963 'Mathis et al. 260g-68() 3,172,834 3/1965 Kozlowski 20S-lll 3,261,879 7/1966 Banks 260-677 DELBERT E. GANTZ, Primary Examiner.

ABRAHAM RIMENS, Examiner. 

1. A PROCESS FOR THE PRODUCTION OF ETHYLENE AND BUTADIENE FROM HYDROCARBONS, WHICH COMRISES THE STEPS OF: CRACKING A HYDROCARBON BOILING WITHIN THE NAPHTHA BOILING RANGE; SEPARATING THE CRACKED EFFLUENT I A FIRST SEPARATIO ZONE TO PRODUCE A GASOLINE STREAM, A C2 STREAM, A C3 STREAM AND A C4 STREAM; SEPARATING BUTADIENE AND ISOBUTENE FROM SAID C4 STREAM AND FEEDING SAID C4 STREAM INTO A BUTENE CONVERION ZONE; CONVERTING BUTENE TO BUTADIENE IN SAID BUTENE CONVERSION ZONE AND COMBINING THE EFFLUENT THREREFROM WITH SAID CRACKED EFFLUENT PRIOR TO SEPARATION THEREOF; PASSING SAID C3 STREAM TO A DISPROPORTIONATION ZONE; IN SAID DISPROPORTIONATION ZONE CONVERTING PROPYLENE TO ETHYLENE AND BUTENE; SEPARATING THE EFFLUENT OF SAID DISPROPORTIONATION ZONE INTO AN ETHYLENE STREAM, A PROPYLENE STEAM AND A BUTENE STREAM; CONVERTING BUTENE OF SAID BUTENE STREAM TO BUTADIENE IN SAID BUTENE CONVERSION ZONE; RECYCLING SAID PROPYLENE STREAM TO SAID DISPROPORTIONATION ZONE; COMBINING SAID ETHYLENE STREAM WITH SAID C2 STREAM; AND SEPARATING SAID C2 STREAM INTO AN ETHYLENE STREAM AND A PRODUCT ETHYLENE STREAM. 